Fibers with fiber diameters smaller than 1 μm, that is, nanometer sized (from several nanometers to several hundreds of nanometers) fibers have gained attention in recent years as revolutionary materials of the future in a broad range of applications such as IT, bio, environmental and other applications. The nanofibers have typically been prepared using an electro-spinning method (henceforth sometimes abbreviated to “ES method”). (See U.S. Pat. No. 1,975,504; You Y., et al Journal of Applied Polymer Science, Vol. 95, p. 193-200, 2005.) However, the ES method is a complicated manufacturing method since polymer needs to be dissolved in solvent and the solvent must be removed from the product obtained. In addition, molecules lack orientation in the filament obtained, and many quality problems such as the presence of small resin particles, referred to as balls and shots were encountered in the fiber aggregates obtained.
The inventors previously invented a means to obtain microfilaments and non-woven fabrics using a super high draw ratio that exceeded one thousand through molecular orientation conducted according to an infrared method. (See Japanese Patent Publication No 2003-166115 and 2004-107851; International Publication No. WO2005/083165A1; Akihiro Suzuki and one other “Journal of Applied Polymer Science”, Vol. 88, p. 3279-3283, 2003; Akihiro Suzuki and one other, “Journal of Applied Polymer Science”, Vol. 92, p. 1449-1453, 2004; Akihiro Suzuki and one other, “Journal of Applied Polymer Science”, Vol. 92, p. 1534-1539, 2004.) These are simple means, and microfilaments with molecular orientation and non-woven fabrics thereof were obtained. The present invention is a further development of the same theme and relates to a means that allows microfilaments to be manufactured continuously and consistently by enabling filaments to be attenuated into nanofilaments.